Superconductor Science and Technology - IOPscience

Superconductor Science and Technology - IOPscience
Superconductor Science and Technology
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Superconductor Science and Technology
is a truly multidisciplinary journal providing an essential forum for members of the superconductivity research community.
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The following article is
Open access
Superconducting high-power cables and lines—development status and technology roadmap
M Noe
et al
2026
Supercond. Sci. Technol.
39
023501
View article
, Superconducting high-power cables and lines—development status and technology roadmap
PDF
, Superconducting high-power cables and lines—development status and technology roadmap
The energy transition requires a tremendous investment in electric grids, mainly due to electrification of heat and mobility sectors and due to the huge expansion of renewable energy. Superconductors offer an extremely high current density while having no resistance. In the past years, the cost-performance of high-temperature superconducting tapes decreased constantly, and the manufacturing capacity was expanded considerably.
In parallel, many AC and DC superconducting cables for various applications from low-voltage up to high-voltage levels have been developed, successfully tested and operated in field tests. The availability of the high-temperature superconducting tapes and the increasing need for network expansion result in an increased interest on the development of superconducting cables.
In this paper, the most important and most recent R&D activities on superconducting cables are summarized. The paper is structured in four main parts. Firstly, an introduction is given not only on the history of R&D but also on the high-temperature superconducting materials and conductors. The main part shows some selected R&D projects in more detail, while in the third part common issues relevant to all cables like cooling are discussed. The paper ends with contributions to hybrid superconducting cables, where electricity transport is combined with chemical energy carriers like liquid hydrogen.
It can be summarized that several projects demonstrated, that superconducting cables can fulfil all technical requirements for a long-term field operation and first permanent installations are realized. Attractive applications for superconducting cables include electric grids, high-current industry bus bars, data centers and aviation.
The following article is
Open access
Roadmap on nanoscale superconductivity for quantum technologies
Oleksandr Dobrovolskiy
et al
2026
Supercond. Sci. Technol.
39
023502
View article
, Roadmap on nanoscale superconductivity for quantum technologies
PDF
, Roadmap on nanoscale superconductivity for quantum technologies
In 2025, the Year of Quantum Science and Technology (
), we celebrate a century of quantum mechanics, witnessing a surge in activities that illuminate its inherent strangeness and drive technological innovation. Superconductivity, discovered 114 years ago, stands as a prime example, offering direct and compelling evidence of macroscopic quantum phenomena. Beyond its ability to conduct immense currents without loss, superconductivity reveals the quantum realm operating on a scale we can directly observe and manipulate. The macroscopic quantum coherence, where an ensemble of particles is described by a single wave function, leads to remarkable consequences: dissipation-less current and flux quantization—the basic properties exploited in superconducting quantum circuit fabrication. This Roadmap has been inspired by intensive discussions and collaborations emerging from the European Cooperation in Science & Technology COST-Action CA21144 (SuperQuMap—Superconducting Nanodevices and Quantum Materials for Coherent Manipulation). The aim of the COST Action SuperQuMap is to establish a strong European network centered on macroscopic quantum behavior in superconductors, bringing together groups of different backgrounds and more than 30 countries. The roadmap outlines the network’s concrete activities, driving advancements in superconductor-based quantum technologies and charting future directions. Spanning fundamental research to practical applications, the roadmap incorporates insights from industry partners developing quantum computation. It begins by exploring quantum materials, highlighting how topology and electronic correlations could catalyze a quantum leap in technology. We then delve into manipulating the superconducting phase, leveraging advancements in magnetism, 3D fabrication, and tunable correlations. Further, we showcase the advanced microscopy techniques—such as angle-resolved photoemission spectroscopy and scanning probes—used to visualize quantum behavior. Finally, and crucially, we detail the quantum devices developed within the network, and their transformative impact on modern quantum computing approaches.
The following article is
Open access
Development of a high current density, high temperature superconducting cable for pulsed magnets
Charlie Sanabria
et al
2024
Supercond. Sci. Technol.
37
115010
View article
, Development of a high current density, high temperature superconducting cable for pulsed magnets
PDF
, Development of a high current density, high temperature superconducting cable for pulsed magnets
A low-AC loss Rare-earth barium copper oxide (REBCO) cable, based on the VIPER cable technology has been developed by commonwealth fusion systems for use in high-field, compact tokamaks. The new cable is composed of partitioned and transposed copper ‘petals’ shaped to fit together in a circular pattern with each petal containing a REBCO tape stack and insulated from each other to reduce AC losses. A stainless-steel jacket adds mechanical robustness—also serving as a vessel for solder impregnation—while a tube runs through the middle for cooling purposes. Additionally, fiber optic sensors are placed under the tape stacks for quench detection (QD). To qualify this design, a series of experiments were conducted as part of the SPARC tokamak central solenoid (CS) model coil program—to retire the risks associated with full-scale, fast-ramping, high-flux high temperature superconductors CS and poloidal field coils for tokamak fusion power plants and net-energy demonstrators. These risk-study and risk-reduction experiments include (1) AC loss measurement and model validation in the range of ∼5 T s
−1
, (2) an IxB electromagnetic (EM) loading of over 850 kN m
−1
at the cable level and up to 300 kN m
−1
at the stack level, (3) a transverse compression resilience of over 350 MPa, (4) manufacturability at tokamak-relevant speeds and scales, (5) cable-to-cable joint performance, (6) fiber optic-based QD speed, accuracy, and feasibility, and (7) overall winding pack integration and magnet assembly. The result is a cable technology, now referred to as PIT VIPER, with AC losses that measure fifteen times lower (at ∼5 T s
−1
) than its predecessor technology; a 2% or lower degradation of critical current (
) at high IxB EM loads; no detectable
degradation up to 600 MPa of transverse compression on the cable unit cell; end-to-end magnet manufacturing, consistently producing
values within 7% of the model prediction; cable-to-cable joint resistances at 20 K on the order of ∼15
nΩ
; and fast, functional QD capabilities that do not involve voltage taps.
The following article is
Open access
Superconducting nanowire single-photon detectors: physics and applications
Chandra M Natarajan
et al
2012
Supercond. Sci. Technol.
25
063001
View article
, Superconducting nanowire single-photon detectors: physics and applications
PDF
, Superconducting nanowire single-photon detectors: physics and applications
Single-photon detectors based on superconducting nanowires (SSPDs or SNSPDs) have rapidly emerged as a highly promising photon-counting technology for infrared wavelengths. These devices offer high efficiency, low dark counts and excellent timing resolution. In this review, we consider the basic SNSPD operating principle and models of device behaviour. We give an overview of the evolution of SNSPD device design and the improvements in performance which have been achieved. We also evaluate device limitations and noise mechanisms. We survey practical refrigeration technologies and optical coupling schemes for SNSPDs. Finally we summarize promising application areas, ranging from quantum cryptography to remote sensing. Our goal is to capture a detailed snapshot of an emerging superconducting detector technology on the threshold of maturity.
The following article is
Open access
The performance of REBCO coated conductor during
in situ
cryogenic irradiation with fusion-spectrum neutrons
K Adams
et al
2026
Supercond. Sci. Technol.
39
02LT01
View article
, The performance of REBCO coated conductor during in situ cryogenic irradiation with fusion-spectrum neutrons
PDF
, The performance of REBCO coated conductor during in situ cryogenic irradiation with fusion-spectrum neutrons
Understanding the tolerance of REBa
Cu
(REBCO) high-temperature superconductors to neutron damage is essential for compact fusion reactor design. Here we report the first
in situ
measurements of the superconducting performance of REBCO coated conductor (CC) during neutron irradiation. The CC was exposed to 14 MeV neutrons at fluxes up to 7.3 × 10
n cm
−2
−1
while carrying current at 40 K.
In situ
voltage measurements revealed no instantaneous disruption of superconductivity, but the critical current (
) decreased linearly with fluence at 0.03 A per 10
12
n cm
−2
. Careful analysis excluded thermal effects as the origin of this degradation. Consistent with a point-defect damage mechanism, superconducting performance was recovered fully following room temperature annealing. This observed onset of
reduction occurred several orders of magnitude below the critical neutron fluences anticipated by previous
ex situ
studies, indicating that service lifetimes of REBCO-based magnets may be substantially shorter than current projections.
The following article is
Open access
Artificial intelligence methods for applied superconductivity: material, design, manufacturing, testing, operation, and condition monitoring
Mohammad Yazdani-Asrami
et al
2022
Supercond. Sci. Technol.
35
123001
View article
, Artificial intelligence methods for applied superconductivity: material, design, manufacturing, testing, operation, and condition monitoring
PDF
, Artificial intelligence methods for applied superconductivity: material, design, manufacturing, testing, operation, and condition monitoring
More than a century after the discovery of superconductors (SCs), numerous studies have been accomplished to take advantage of SCs in physics, power engineering, quantum computing, electronics, communications, aviation, healthcare, and defence-related applications. However, there are still challenges that hinder the full-scale commercialization of SCs, such as the high cost of superconducting wires/tapes, technical issues related to AC losses, the structure of superconducting devices, the complexity and high cost of the cooling systems, the critical temperature, and manufacturing-related issues. In the current century, massive advancements have been achieved in artificial intelligence (AI) techniques by offering disruptive solutions to handle engineering problems. Consequently, AI techniques can be implemented to tackle those challenges facing superconductivity and act as a shortcut towards the full commercialization of SCs and their applications. AI approaches are capable of providing fast, efficient, and accurate solutions for technical, manufacturing, and economic problems with a high level of complexity and nonlinearity in the field of superconductivity. In this paper, the concept of AI and the widely used algorithms are first given. Then a critical topical review is presented for those conducted studies that used AI methods for improvement, design, condition monitoring, fault detection and location of superconducting apparatuses in large-scale power applications, as well as the prediction of critical temperature and the structure of new SCs, and any other related applications. This topical review is presented in three main categories: AI for large-scale superconducting applications, AI for superconducting materials, and AI for the physics of SCs. In addition, the challenges of applying AI techniques to the superconductivity and its applications are given. Finally, future trends on how to integrate AI techniques with superconductivity towards commercialization are discussed.
The following article is
Open access
High power density superconducting rotating machines—development status and technology roadmap
Kiruba S Haran
et al
2017
Supercond. Sci. Technol.
30
123002
View article
, High power density superconducting rotating machines—development status and technology roadmap
PDF
, High power density superconducting rotating machines—development status and technology roadmap
Superconducting technology applications in electric machines have long been pursued due to their significant advantages of higher efficiency and power density over conventional technology. However, in spite of many successful technology demonstrations, commercial adoption has been slow, presumably because the threshold for value versus cost and technology risk has not yet been crossed. One likely path for disruptive superconducting technology in commercial products could be in applications where its advantages become key enablers for systems which are not practical with conventional technology. To help systems engineers assess the viability of such future solutions, we present a technology roadmap for superconducting machines. The timeline considered was ten years to attain a Technology Readiness Level of 6+, with systems demonstrated in a relevant environment. Future projections, by definition, are based on the judgment of specialists, and can be subjective. Attempts have been made to obtain input from a broad set of organizations for an inclusive opinion. This document was generated through a series of teleconferences and in-person meetings, including meetings at the 2015 IEEE PES General meeting in Denver, CO, the 2015 ECCE in Montreal, Canada, and a final workshop in April 2016 at the University of Illinois, Urbana-Champaign that brought together a broad group of technical experts spanning the industry, government and academia.
The following article is
Open access
Analytical approximations for the self-field distribution of a superconducting tape between iron cores
Luning Hao
et al
2022
Supercond. Sci. Technol.
35
125009
View article
, Analytical approximations for the self-field distribution of a superconducting tape between iron cores
PDF
, Analytical approximations for the self-field distribution of a superconducting tape between iron cores
Magnetic switches apply AC magnetic fields to DC current-carrying high temperature superconducting (HTS) tapes to generate DC voltages and are commonly used in the persistent current switches (PCSs) and flux pumps to charge HTS-coated conductor magnets. Normally, they are made of copper field coils and iron cores with narrow air gaps for the HTS tape to pass through. However, the perpendicular components of the self-field of the HTS tape in the air gap can be enhanced by the iron cores and cause a critical current reduction of up to 40% to the tape. If ignored, this reduction, rather than the magnets themselves, will limit the current carrying capability of the HTS magnets. To tackle this problem, we present analytical approximations to calculate the self-field distribution of a superconducting tape between iron cores. The approximate solutions are based on the method of images in electromagnetics to simplify the derivation and are then verified by the experiments and 3D finite element method models using the T–A formulation. The solutions are universal and can be applied to almost all the magnetic switches currently in use. A case study of typical magnetic switches shows that the solutions can be used to determine the critical current reduction quickly and accurately, analyse the influence of different parameters, and simplify the design process of magnetic switches. The results can significantly benefit the design and optimisation of PCSs and flux pumps for HTS magnet charging systems in the future.
The following article is
Open access
REBCO coated conductors: enabling the next generation of tokamak reactors
Xiaodong Li
et al
2025
Supercond. Sci. Technol.
38
033001
View article
, REBCO coated conductors: enabling the next generation of tokamak reactors
PDF
, REBCO coated conductors: enabling the next generation of tokamak reactors
The discovery of rare-earth barium copper oxide (REBCO) materials with high critical temperatures, and the continued advancements in the fabrication of REBCO coated conductors with extremely high critical current densities, has enabled the development of ultra-high-field (>20 T) compact and large-scale thermonuclear fusion devices. At present, around a dozen global commercial manufacturers are able to supply high-quality REBCO coated conductors with excellent performance. Significant advancements have been made for high-temperature, low-field applications such as motors, generators, long-length transmission cables, and so on using REBCO coated conductors. Nonetheless, multiple ongoing critical challenges under low-temperature, high-field conditions, such as irreversible degradation of the critical current, along with insufficient mechanical protection and inadequate reduction of AC losses, remain unsolved, collectively hindering their utilization in high-field thermonuclear fusion reactors. This paper provides a comprehensive theoretical and technical review of the current state-of-the-art, associated challenges, and prospects in the research and development (R&D) of REBCO coated conductors, cables, and magnet systems for high-field fusion. It highlights the significant enhancements in current-carrying capacity, mechanical protection, and AC loss reduction achieved over the past decade. The paper delves into detailed analyses of potential cabling solutions that offer exceptional current-carrying capacity while ensuring an optimal inductance balance for toroidal, poloidal, and central solenoid coils in tokamak devices. This work endeavours to lay the groundwork for the R&D of the next-generation REBCO magnets to facilitate the construction of ultra-high-field compact and large-scale tokamak reactors.
The following article is
Open access
A strategic roadmap for implementing superconductivity towards zero-emission transport
Marco Breschi
et al
2026
Supercond. Sci. Technol.
39
011001
View article
, A strategic roadmap for implementing superconductivity towards zero-emission transport
PDF
, A strategic roadmap for implementing superconductivity towards zero-emission transport
Superconductivity is an essential technology for reducing carbon emissions and electrifying the transportation sector. Its unique ability to provide higher power density and greater efficiency sets it apart from other technologies. This document outlines a plan for integrating superconducting technology into the transportation sector, identifying major challenges and interim steps to be taken to overcome them. Implementing this plan and securing public and private funds will help transition the transportation sector towards zero-emission aircraft, high-capacity efficient shipping, and widespread use of a superconductivity-liquid hydrogen energy platform for transportation.
The following article is
Open access
Simulation of Meissner state and flux penetration in thin film superconductors in perpendicular field
F Semper
et al
2026
Supercond. Sci. Technol.
39
045014
View article
, Simulation of Meissner state and flux penetration in thin film superconductors in perpendicular field
PDF
, Simulation of Meissner state and flux penetration in thin film superconductors in perpendicular field
We present a comprehensive modeling framework to analyze the magnetic response of type-II superconductors in both the Meissner and mixed states, in the limit of thin-film geometries. Starting from the fluxoid quantization condition, we compute the magnetic susceptibility and its dependence on the penetration depth
, highlighting the experimental resolution needed to detect small variations in
. To describe the penetration of vortices in the mixed state, we implement a critical state model that imposes local current constraints, enabling simulation of magnetization curves in samples with and without weak links, such as grain boundaries. The flux penetration of the virgin magnetization curves of rectangular thin films exhibit quadratic dependency on the applied field, contrary to Brandt and Indenbom (1993
Phys. Rev. B
48
12893–906) cubic prediction owing to his simplification of the problem by assuming an infinitely long strip. Two complementary approaches-numerical minimization and flux front tracking yield consistent predictions for magnetization and allow extraction of both intra- and intergranular critical current densities. The simulated magnetic response, including subtle features in the derivative of magnetization with respect to the applied field, is in excellent agreement with experimental AC susceptibility measurements on single- and bicrystalline thin films.
Parameterization of the critical current of low-loss, high current-density Bi-2212 as a function of magnetic field and temperature
A Godeke
et al
2026
Supercond. Sci. Technol.
39
045013
View article
, Parameterization of the critical current of low-loss, high current-density Bi-2212 as a function of magnetic field and temperature
PDF
, Parameterization of the critical current of low-loss, high current-density Bi-2212 as a function of magnetic field and temperature
A physics-based parameterization of the critical current as a function of magnetic field and temperature
has been developed for multi-filamentary, low alternating-current-loss, high current-density (
(Bi-2212) superconducting round wire. The parameterization was developed using
data that were measured in applied magnetic fields
T, and in temperatures
K, and is valid across the entire measurement range. The parameterization uses a tri-exponential decay of the critical current with increasing magnetic field, highlighting three distinct current paths through the polycrystalline material: One for strongly connected grains, and two for weakly connected grains, which are most likely directly related to three sets of grain-alignment angles. Such analyses therefore enable probing of the internal grain-connectivity from a common 4-point
-measurement. An accurate description of
across the functional field-temperature parameter-space is furthermore critical for application design, which requires reliable parameterizations.
Prototype HTS magnet system with sub-ppm field ripple wirelessly powered by HTS transformer–rectifier
Yi Lin
et al
2026
Supercond. Sci. Technol.
39
045012
View article
, Prototype HTS magnet system with sub-ppm field ripple wirelessly powered by HTS transformer–rectifier
PDF
, Prototype HTS magnet system with sub-ppm field ripple wirelessly powered by HTS transformer–rectifier
High-temperature superconducting (HTS) magnets are promising for nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) applications since they can generate higher magnetic fields and work at higher temperatures. However, due to various sources of loss, HTS NMR/MRI magnets normally have to work in current driven mode, incurring significant cryogenic heat load and inferior magnetic field stability compared to persistent current operation of low-temperature superconducting magnets. This work demonstrates using a magnetic field controlled HTS transformer–rectifier and high-resolution NMR probe measurement feedback to wirelessly power closed-loop HTS magnets with high temporal stability. We achieve less than ±8 ppb h
−1
long-term field drift and ±0.19 ppm min
−1
short-term field ripple in an HTS test magnet with a time constant less than 30 000 s, setting a temporal stability record for quasi-persistent operation HTS magnets. By eliminating current leads and compensating for screening current drift, this work provides a potential engineering pathway of magnetic field stabilization for future HTS NMR/MRI applications.
The following article is
Open access
Positive influence of femtosecond pulsed laser machining on levitation forces of top-seeded melt-grown textured YBCO
F Al-Mokdad
et al
2026
Supercond. Sci. Technol.
39
045011
View article
, Positive influence of femtosecond pulsed laser machining on levitation forces of top-seeded melt-grown textured YBCO
PDF
, Positive influence of femtosecond pulsed laser machining on levitation forces of top-seeded melt-grown textured YBCO
High-temperature textured YBCO superconductors are considered relevant for applications requiring strong flux pinning, and hence enhanced critical current density and resilient levitation forces, such as maglev systems, magnetic resonance imaging and nuclear magnetic resonance magnets. Improving the performance of YBCO for such applications is commonly achieved by enhancing the flux pinning properties through various mechanisms. In addition, either related to the sample fabrication process or demanded by the final operation conditions, machining these highly brittle samples would be desirable for a number of applications and is a challenging demand. This work reports on the use of ultrashort-pulsed laser irradiation to machine holes into top-seeded melt-growth YBCO samples and how this processing affects their microstructure and superconducting behavior. The x-ray diffraction (XRD) and scanning electron microscopy results demonstrate that ultrashort-pulsed laser machining can create well-defined holes with diminishing microstructural damage. The superconducting properties of the laser-machined samples are essentially preserved, even compatible with the enhancement in the critical current density and levitation force properties. These findings demonstrate the potential of ultrashort-pulsed lasers as a viable tool for machining textured YBCO products and enhancing their performance without degrading their functional properties. This method paves the way towards the generation of artificial defects, machining and shaping of high
superconductor ceramics into precisely well-defined complex geometries relevant for power applications.
The following article is
Open access
SCSC-IFB cable: a novel low-AC-loss cable composed of multifilament coated conductors with superconducting inter-filament bridges
Naoyuki Amemiya
et al
2026
Supercond. Sci. Technol.
39
045010
View article
, SCSC-IFB cable: a novel low-AC-loss cable composed of multifilament coated conductors with superconducting inter-filament bridges
PDF
, SCSC-IFB cable: a novel low-AC-loss cable composed of multifilament coated conductors with superconducting inter-filament bridges
Current sharing between filaments is necessary in multifilament coated conductors to bypass local defects arising from the fabrication process and to impede current transport in each filament. We propose a novel cable concept, termed the spiral copper-plated striated coated conductor with inter-filament bridges cable (SCSC-IFB cable). In this design, copper-plated multifilament (striated) coated conductors incorporating IFBs—non-striated sections between filaments—are helically wound around a central core. In contrast to current sharing through copper plating,
i.e.
, the current meandering through it to avoid local defects on filaments, which generates a small but finite voltage, current sharing through IFBs produces no voltage and thereby does not affect the electric field–current characteristics of multifilament coated conductors. Similar to twisting in conventional low
superconductors, helical cabling decouples filaments electromagnetically against a transverse alternating current (AC) magnetic field. We experimentally confirmed that IFBs improve the electric field–current characteristics,
i.e.
, the
-values, and that the helical cabling does not affect them, by using 2 mm-wide copper-plated 10-filament coated conductors with IFBs. Using the same coated conductors, we wound short pieces of the monolayer SCSC-IFB cables and examined their AC loss characteristics under a transverse AC magnetic field at 77 K. Importantly, the bridge intervals were designed to exceed half the cabling pitch, preventing superconducting loop currents through two IFBs that could otherwise couple the filaments. The measured coupling time constant was 19
s, which is sufficiently small for a wide range of applications. Furthermore, the magnitudes of the measured magnetisation losses above the penetration field of each filament are nearly identical to the theoretical values predicted for cables composed of multifilament coated conductors with electromagnetically decoupled filaments.
The principle, preparation and development of magnetoresistance/superconducting composite magnetic sensors
Siyuan Han
et al
2026
Supercond. Sci. Technol.
39
033001
View article
, The principle, preparation and development of magnetoresistance/superconducting composite magnetic sensors
PDF
, The principle, preparation and development of magnetoresistance/superconducting composite magnetic sensors
Weak magnetic detection plays an important role in life, demonstrating enormous potential and application value in fields such as healthcare, transportation, and military. With the increasing demand for weak magnetic field detection, a new type of magnetoresistance/superconducting composite magnetic sensor has been successfully developed in recent years. It combines superconducting magnetic concentration technology and magnetic sensing technology, and unleashes the potential of both in weak magnetic detection. In terms of magnetic field detection accuracy, it is expected to reach the fT level and has demonstrated the possibility of large-scale application in the field of weak magnetic detection. This article reviews the structure and principle of magnetoresistance/superconducting composite magnetic sensors, and introduces the preparation and development of giant magnetoresistance/superconducting composite magnetic sensors and tunneling magnetoresistance/superconducting composite magnetic sensors, respectively.
The following article is
Open access
Roadmap on nanoscale superconductivity for quantum technologies
Oleksandr Dobrovolskiy
et al
2026
Supercond. Sci. Technol.
39
023502
View article
, Roadmap on nanoscale superconductivity for quantum technologies
PDF
, Roadmap on nanoscale superconductivity for quantum technologies
In 2025, the Year of Quantum Science and Technology (
), we celebrate a century of quantum mechanics, witnessing a surge in activities that illuminate its inherent strangeness and drive technological innovation. Superconductivity, discovered 114 years ago, stands as a prime example, offering direct and compelling evidence of macroscopic quantum phenomena. Beyond its ability to conduct immense currents without loss, superconductivity reveals the quantum realm operating on a scale we can directly observe and manipulate. The macroscopic quantum coherence, where an ensemble of particles is described by a single wave function, leads to remarkable consequences: dissipation-less current and flux quantization—the basic properties exploited in superconducting quantum circuit fabrication. This Roadmap has been inspired by intensive discussions and collaborations emerging from the European Cooperation in Science & Technology COST-Action CA21144 (SuperQuMap—Superconducting Nanodevices and Quantum Materials for Coherent Manipulation). The aim of the COST Action SuperQuMap is to establish a strong European network centered on macroscopic quantum behavior in superconductors, bringing together groups of different backgrounds and more than 30 countries. The roadmap outlines the network’s concrete activities, driving advancements in superconductor-based quantum technologies and charting future directions. Spanning fundamental research to practical applications, the roadmap incorporates insights from industry partners developing quantum computation. It begins by exploring quantum materials, highlighting how topology and electronic correlations could catalyze a quantum leap in technology. We then delve into manipulating the superconducting phase, leveraging advancements in magnetism, 3D fabrication, and tunable correlations. Further, we showcase the advanced microscopy techniques—such as angle-resolved photoemission spectroscopy and scanning probes—used to visualize quantum behavior. Finally, and crucially, we detail the quantum devices developed within the network, and their transformative impact on modern quantum computing approaches.
Studies of superconductivity of Fe chalcogenides in films grown by PLD technique
Atsutaka Maeda
et al
2026
Supercond. Sci. Technol.
39
023001
View article
, Studies of superconductivity of Fe chalcogenides in films grown by PLD technique
PDF
, Studies of superconductivity of Fe chalcogenides in films grown by PLD technique
Studies on Fe chalcogenide superconductor using thin films grown by the PLD technique are reviewed in terms of electronic phase diagram, properties in the normal state, properties in the superconducting state, together with the comparison with properties in bulk crystals, molecular beam epitaxy grown films and exfoliated crystals. Challenges to increase superconducting
will also be introduced.
The following article is
Open access
Superconducting high-power cables and lines—development status and technology roadmap
M Noe
et al
2026
Supercond. Sci. Technol.
39
023501
View article
, Superconducting high-power cables and lines—development status and technology roadmap
PDF
, Superconducting high-power cables and lines—development status and technology roadmap
The energy transition requires a tremendous investment in electric grids, mainly due to electrification of heat and mobility sectors and due to the huge expansion of renewable energy. Superconductors offer an extremely high current density while having no resistance. In the past years, the cost-performance of high-temperature superconducting tapes decreased constantly, and the manufacturing capacity was expanded considerably.
In parallel, many AC and DC superconducting cables for various applications from low-voltage up to high-voltage levels have been developed, successfully tested and operated in field tests. The availability of the high-temperature superconducting tapes and the increasing need for network expansion result in an increased interest on the development of superconducting cables.
In this paper, the most important and most recent R&D activities on superconducting cables are summarized. The paper is structured in four main parts. Firstly, an introduction is given not only on the history of R&D but also on the high-temperature superconducting materials and conductors. The main part shows some selected R&D projects in more detail, while in the third part common issues relevant to all cables like cooling are discussed. The paper ends with contributions to hybrid superconducting cables, where electricity transport is combined with chemical energy carriers like liquid hydrogen.
It can be summarized that several projects demonstrated, that superconducting cables can fulfil all technical requirements for a long-term field operation and first permanent installations are realized. Attractive applications for superconducting cables include electric grids, high-current industry bus bars, data centers and aviation.
Irradiation effects and performance evolution in REBCO superconductors: mechanisms, characterization, and applications
Jinxing Zheng
et al
2026
Supercond. Sci. Technol.
39
013001
View article
, Irradiation effects and performance evolution in REBCO superconductors: mechanisms, characterization, and applications
PDF
, Irradiation effects and performance evolution in REBCO superconductors: mechanisms, characterization, and applications
This review provides a detailed examination of the irradiation-induced effects in REBCO (rare earth barium copper oxide) high-temperature superconductors, with a particular focus on YBa
Cu
7–
(YBCO) systems. Various irradiation sources—including protons, helium ions, neutrons, heavy ions, gamma rays, and deuterium plasma—are systematically compared in terms of their damage mechanisms, defect morphologies, and subsequent influence on superconducting properties such as the critical temperature (
) and critical current density (
). It is shown that low to moderate doses can enhance flux pinning by introducing tailored defect structures, whereas excessive irradiation leads to structural degradation and suppression of superconducting performance. This review synthesizes recent findings across a wide range of irradiation fluences and energies, highlighting key experimental techniques—for defect characterization, and further provides an overview of simulation approaches commonly employed to model irradiation-induced processes. Special attention is given to the non-monotonic relationship between irradiation dose and
, the role of artificial pinning centers, and the comparative responses of REBCO variants. The outlook discusses outstanding challenges in correlating atomic-scale damage with macroscopic performance, the importance of
in-situ
diagnostics, and the integration of empirical data with multiscale simulation frameworks for guiding the development of radiation-tolerant superconductors in fusion, aerospace, and high-energy physics applications.
Optical Evidence of eV-Scale Spectral Weight Redistribution in (Cu, C)-1234 Thin Film
孙 et al
View accepted manuscript
, Optical Evidence of eV-Scale Spectral Weight Redistribution in (Cu, C)-1234 Thin Film
PDF
, Optical Evidence of eV-Scale Spectral Weight Redistribution in (Cu, C)-1234 Thin Film
We report a broadband spectroscopic-ellipsometry study of high-quality (Cu, C)Ba2Ca3Cu4Oy thin films (hereafter abbreviated as (Cu, C)-1234), aimed at tracking the temperature dependence of the electronic structure from 0.5 to 4.2 eV. From the extracted complex dielectric function, we obtain the real optical conductivity σ1 (ω) and quantify spectral-weight redistribution in four energy windows that separate the low-energy intraband response in contrast to the mid- and high-energy Cu-O interband/charge-transfer excitations. Upon cooling, the spectra display a redistribution of optical spectral weight that spans more than 1 eV, far larger than the superconducting gap, indicating correlation effects beyond a weak-coupling picture. The low-energy intraband spectral weight is suppressed near a pairing-onset temperature Tconset and partially recovers below the zero-resistance temperature Tc0, while weight in Zhang-Rice-singlet and LHB-UHB charge-transfer channels increases, with the largest high-energy enhancement appearing at or just below Tc0. These observations may indicate a two-stage evolution of the electronic structure, in which precursor pairing or phase fluctuations first reduce the single-particle coherence, followed by further spectral reorganization at lower temperatures. However, considering the relatively broad resistive transition of the film, the observed spectral-weight changes may also be influenced by percolative superconductivity or by a distribution of local transition temperature in the film. This eV-scale spectral-weight redistribution may reflect related electronic or lattice effects discussed in previous studies of cuprates. Our results demonstrate that low- and high-energy electronic degrees of freedom are cooperatively involved in the superconducting transition of multilayer cuprates, thereby motivating layer-resolved spectroscopies and theoretical efforts to clarify the microscopic coupling mechanisms.
Current Carrying Performance of CORC-CICC Conductor During Fabrication and Transverse Loading
Li et al
View accepted manuscript
, Current Carrying Performance of CORC-CICC Conductor During Fabrication and Transverse Loading
PDF
, Current Carrying Performance of CORC-CICC Conductor During Fabrication and Transverse Loading
The application of Conductor on Round Core (CORC) cables in cablein-conduit conductor (CICC) configurations subjects the conductor to complex electromagnetic and mechanical conditions during fabrication and operation. In this work, the evolution of the current-carrying performance of a CORC-CICC conductor under twisting, compaction, and transverse loading is investigated through combined experimental testing and numerical modeling. Transport current measurements are first carried out on CORC-CICC samples at different fabrication stages and under stepwise transverse compressive loads. An equivalent layer-wise electromagnetic model suitable for multi-layer CORC and CICC structures is then developed, which significantly reduces the computational cost of three-dimensional twisted simulations while maintaining accurate critical current prediction. In addition, a continuous three-dimensional mechanical model covering subcable twisting, jacket compaction, springback, and transverse compression is established to analyze the stress evolution within the conductor. The results indicate that the transverse load is predominantly supported by the stainless-steel jacket, with limited stress transferred to the superconducting tapes. Good agreement between experimental observations and numerical predictions confirms the effectiveness of the combined electromagnetic-mechanical modeling approach for CORC-CICC conductors.
The following article is
Open access
Ultra-long fiber Bragg grating arrays for quenchprotection in HTS magnets: A numerical analysis
Muhammad Haneef et al
View accepted manuscript
, Ultra-long fiber Bragg grating arrays for quenchprotection in HTS magnets: A numerical analysis
PDF
, Ultra-long fiber Bragg grating arrays for quenchprotection in HTS magnets: A numerical analysis
We present a numerical model to characterize the spectral response of ultra-long fiber Bragg grating (ULFBG) arrays for potential use in superconducting quench detection. The model is built using the transfer matrix method and the coupled mode theory to simulate the spectral response of the grating array. It incorporates a statistical distribution of grating parameters, such as Bragg wavelength, index modulation depth, grating length, and spacing, to realistically represent fabrication-induced variations commonly observed in ultralong FBG arrays. To address coherence induced spectral distortions, a generic intensity matrix approach is implemented. The model is applied to simulate the sensor response under quench-like conditions, specifically, small thermal excursions at cryogenic temperatures. Simulated results are validated against controlled experimental data, demonstrating good agreement and confirming the model’s ability to accurately capture the broadened spectral features observed in practice. This modeling framework supports the development of ULFBG-based optical sensing systems for high-resolution quench detection in superconducting environments.
Superconductivity in Al-based high-entropy alloys TiHfNbTaAl and TaNbHfZrAl
Huang et al
View accepted manuscript
, Superconductivity in Al-based high-entropy alloys TiHfNbTaAl and TaNbHfZrAl
PDF
, Superconductivity in Al-based high-entropy alloys TiHfNbTaAl and TaNbHfZrAl
Since the first report of a high-entropy alloy (HEA) superconductor in 2014, HEAs have continued to captivate the interest of superconducting researchers. Owing to the significant degree of disorder inherent in these systems, they serve as exemplary models for examining the properties of materials that exist in states intermediate between crystalline and amorphous structures. Here we present the superconductivity properties and crystal structure of TaNbHfZrAl and TiHfNbTaAl HEAs, which both have the VEC of 4.2 and body-centered cubic (BCC) structure. Through resistivity, magnetic, and specific heat measurements, we prove that both samples are the bulk type-II superconductors with a critical temperature Tc of 5.5 K for TaNbHfZrAl and Tc of 3.2 K for TiHfNbTaAl. The Tc of HEA superconductors is influenced by the VEC and the element composition. And the incorporation of Al in high disorder HEA superconductors causes a more crystallinelike Tc dependence. We also found that the ∆Cel/γT_"c" ^"mid" (2.31) and 2∆0/KBTc (4.48) of the TaNbHfZrAl sample are close to the known strongly coupled systems, suggesting that it is a strongly coupled superconductor. The TaNbHfZrAl HEA system serves as a novel material platform for exploring strongly coupled phenomena.
Defect detection of high-temperature superconducting coil
Zhao et al
View accepted manuscript
, Defect detection of high-temperature superconducting coil
PDF
, Defect detection of high-temperature superconducting coil
Due to the intrinsic brittleness of high-temperature superconducting materials, local defects are prone to occur during the winding of coils, which poses significant risks to the safe operation of magnets. This study proposes a coil defect detection method that utilizes a sensor matrix to measure the temperature distribution and propagation process on the coil under current-carrying conditions. The location of the defects can be traced through an inversion algorithm. This paper introduces the design, construction, and test results of the experimental setup. It has been verified that the method can effectively detect localized heat generation as low as 0.01 W, which corresponds to a local defect in coils with a 10% critical current reduction.
More Accepted manuscripts
The following article is
Open access
Simulation of Meissner state and flux penetration in thin film superconductors in perpendicular field
F Semper
et al
2026
Supercond. Sci. Technol.
39
045014
View article
, Simulation of Meissner state and flux penetration in thin film superconductors in perpendicular field
PDF
, Simulation of Meissner state and flux penetration in thin film superconductors in perpendicular field
We present a comprehensive modeling framework to analyze the magnetic response of type-II superconductors in both the Meissner and mixed states, in the limit of thin-film geometries. Starting from the fluxoid quantization condition, we compute the magnetic susceptibility and its dependence on the penetration depth
, highlighting the experimental resolution needed to detect small variations in
. To describe the penetration of vortices in the mixed state, we implement a critical state model that imposes local current constraints, enabling simulation of magnetization curves in samples with and without weak links, such as grain boundaries. The flux penetration of the virgin magnetization curves of rectangular thin films exhibit quadratic dependency on the applied field, contrary to Brandt and Indenbom (1993
Phys. Rev. B
48
12893–906) cubic prediction owing to his simplification of the problem by assuming an infinitely long strip. Two complementary approaches-numerical minimization and flux front tracking yield consistent predictions for magnetization and allow extraction of both intra- and intergranular critical current densities. The simulated magnetic response, including subtle features in the derivative of magnetization with respect to the applied field, is in excellent agreement with experimental AC susceptibility measurements on single- and bicrystalline thin films.
The following article is
Open access
Ultra-long fiber Bragg grating arrays for quenchprotection in HTS magnets: A numerical analysis
Shahna Muhammad Haneef
et al
2026
Supercond. Sci. Technol.
View article
, Ultra-long fiber Bragg grating arrays for quenchprotection in HTS magnets: A numerical analysis
PDF
, Ultra-long fiber Bragg grating arrays for quenchprotection in HTS magnets: A numerical analysis
We present a numerical model to characterize the spectral response of ultra-long fiber Bragg grating (ULFBG) arrays for potential use in superconducting quench detection. The model is built using the transfer matrix method and the coupled mode theory to simulate the spectral response of the grating array. It incorporates a statistical distribution of grating parameters, such as Bragg wavelength, index modulation depth, grating length, and spacing, to realistically represent fabrication-induced variations commonly observed in ultralong FBG arrays. To address coherence induced spectral distortions, a generic intensity matrix approach is implemented. The model is applied to simulate the sensor response under quench-like conditions, specifically, small thermal excursions at cryogenic temperatures. Simulated results are validated against controlled experimental data, demonstrating good agreement and confirming the model’s ability to accurately capture the broadened spectral features observed in practice. This modeling framework supports the development of ULFBG-based optical sensing systems for high-resolution quench detection in superconducting environments.
The following article is
Open access
HTS Single-Balanced Mixer Design and Measurement
Timothy Lawrence Cosgrove
et al
2026
Supercond. Sci. Technol.
View article
, HTS Single-Balanced Mixer Design and Measurement
PDF
, HTS Single-Balanced Mixer Design and Measurement
This paper presents the modelling, simulation, and measurement of a 9.5 GHz to 10 GHz high-temperature superconducting (HTS) single-balanced mixer. A complete design methodology is proposed for the circuit topology. This includes a 3 dB branchline hybrid coupler, a 6th-order impedance matching network for a lumped-element load impedance HTS Josephson junction (JJ) model, high and low frequency grounding structure and a compact low-pass filter. The full circuit topology is implemented on a 40 mm x 25 mm x 0.5 mm YBa_2 Cu_3 O_(7-x) (YBCO) /Magnesium Oxide (MgO) substrate. The predicted conversion loss based on our typical junction parameters at 40 K is 3.24 dB. The device demonstrated a very low optimal local oscillator (LO) power of -50 dBm and achieved the highest possible 1 dB compression point under these conditions. The measured junctions showed initial discrepancies from the typical and expected performance, compared to previous works using the same manufacturing process. Supplementary simulations using the measured HTS JJ parameters showed that the conversion gain and radio frequency (RF) bandwidth closely aligned with the measured results, validating the design approach and emphasising the importance of optimising the HTS JJ parameters. This work provides a foundational methodology for HTS single-balanced mixers and highlights potential solutions for future iterations to enhance the overall performance.
The following article is
Open access
Dependence of the superconducting transition temperature on the electronic density of states and lattice parameter in pulsed laser deposited niobium nitride thin films
Zeyou Li
et al
2026
Supercond. Sci. Technol.
View article
, Dependence of the superconducting transition temperature on the electronic density of states and lattice parameter in pulsed laser deposited niobium nitride thin films
PDF
, Dependence of the superconducting transition temperature on the electronic density of states and lattice parameter in pulsed laser deposited niobium nitride thin films
High quality epitaxial niobium nitride (NbN) thin films were grown on MgO (001) substrates by pulsed laser deposition (PLD) from a pure NbN target while varying the nitrogen partial pressure inside the chamber. This variation provides an additional degree of freedom in the film formation: by adjusting the nitrogen partial pressure, we systematically modify the lattice parameter of the δ-NbN phase systematically, and tune the superconducting transition temperature (Tc). X-ray Diffraction (XRD) and Hall conductivity measurements show that this change in Tc arises from the combined influence of lattice strain, and carrier concentration. A phenomenological analysis based on the McMillan and Allen Dynes strong coupling models closely captures the observed trends. Our results demonstrate that rational design of epitaxial superconducting materials, essential for interface control of physical properties, can be achieved by tuning the lattice parameter and carrier concentration in δ-NbN. Furthermore, our results provide a pathway to separate intrinsic structural factors affecting the transition temperature from proximity-induced effects in superconducting hybrid structures.
The following article is
Open access
Atomic-layer deposited mid-infrared sensitive NbTiN superconducting nanowire single photon detectors
Nidhi Choudhary
et al
2026
Supercond. Sci. Technol.
View article
, Atomic-layer deposited mid-infrared sensitive NbTiN superconducting nanowire single photon detectors
PDF
, Atomic-layer deposited mid-infrared sensitive NbTiN superconducting nanowire single photon detectors
The advancement of superconducting nanowire single photon detectors (known as SNSPDs or SSPDs) is intrinsically linked to breakthroughs in superconducting materials engineering. These detectors are prized for their excellent sensitivity and performance across a wide wavelength range, from UV to mid-infrared. Plasmaenhanced atomic layer deposition (ALD) is an advanced deposition technique that enables exceptional film uniformity across large wafers, making it ideal for a variety of applications. In this study, ALD NbTiN films are fabricated into SNSPDs that exhibit single-photon response from near-to mid -infrared wavelengths. A 5 nm thick NbTiN film was patterned into devices consisting of ~100 nm wide meandered nanowires, and the nanowire crosssection and composition was analysed by transmission electron microscopy (TEM). The devices were tested in a closed-cycle cryostat with a base temperature of 0.9 K. Photon detection rate and timing jitter were measured across the wavelength range 1.5 -4.4 µm under low dark count conditions, confirming single-photon sensitivity across the measured wavelength bands. This work introduces the ALD-grown films as a new platform for SNSPD detectors, achieving mid-infrared detection. The intact film quality after fabrication demonstrates the potential of ALD processes for scalable infrared detector technologies.
The following article is
Open access
Improvement of superconducting Ta films on sapphire via controlled vacuum annealing
Yihui Sun
et al
2026
Supercond. Sci. Technol.
View article
, Improvement of superconducting Ta films on sapphire via controlled vacuum annealing
PDF
, Improvement of superconducting Ta films on sapphire via controlled vacuum annealing
This study systematically investigates the improvement of superconducting properties in Ta films through controlled annealing processes. We focus on the Ta films deposited at room temperature using Nb as the buffer layer, which exhibits excellent performance in superconducting quantum circuits. It is found that, prolonged annealing under limited vacuum conditions leads to degradation of superconducting performance due to the incorporation of oxygen elements. By reducing the annealing time to maintain improved vacuum conditions, combined with an ion beam etching (IBE) cleaning process on the film surface, we successfully increased the residual resistivity ratio (RRR) of the film from 3.65 to 4.57. Furthermore, by optimizing the annealing temperature at a fixed duration, the RRR was further improved to 4.84. Characterization of structure and surface morphology confirms the enhanced crystallinity and reduced surface roughness in the annealed samples. Our results indicates that surface cleaning and vacuum quality of annealing environment are key factors determining the quality of the annealed Ta films.
The following article is
Open access
Rapid liquid facilitated amorphous-to-crystalline (LAC) pulsed laser deposition method for growth of high JC REBCO thin films
John Patrick Frederick Feighan
et al
2026
Supercond. Sci. Technol.
View article
, Rapid liquid facilitated amorphous-to-crystalline (LAC) pulsed laser deposition method for growth of high JC REBCO thin films
PDF
, Rapid liquid facilitated amorphous-to-crystalline (LAC) pulsed laser deposition method for growth of high JC REBCO thin films
We report on a method for producing high critical current density (Jc) thin films of GdBa2Cu3O7 (GdBCO) using pulsed laser deposition (PLD) at fast rates. This method utilises a two-step liquid facilitated amorphous-to-crystalline (LAC) transformation process. The process involves the vacuum deposition of an amorphous Cu-rich GdBCO layer, followed by a controlled increase in the film temperature and oxygen partial pressure (pO2) to convert the amorphous layer into epitaxial crystalline GdBCO. X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) measurements revealed that both the oxygen content of the PLD targets and elemental evaporation during heating are key factors in successfully growing high quality films. GdBCO films fabricated with the LAC method show a Tc of 91.6 K and Jc values comparable to or exceeding those of standard one-step-crystallised PLD films grown three times more slowly. With a deposition speed of 150 nm/min and a one-minute film conversion time, the ex-situ LAC process represents a promising method for fast REBCO (RE= rare earth) coated conductor film fabrication, potentially overcoming the drawback of tighter process controls needed for standard in-situ fabrication of REBCO by PLD.
The following article is
Open access
Positive influence of femtosecond pulsed laser machining on levitation forces of top-seeded melt-grown textured YBCO
F Al-Mokdad
et al
2026
Supercond. Sci. Technol.
39
045011
View article
, Positive influence of femtosecond pulsed laser machining on levitation forces of top-seeded melt-grown textured YBCO
PDF
, Positive influence of femtosecond pulsed laser machining on levitation forces of top-seeded melt-grown textured YBCO
High-temperature textured YBCO superconductors are considered relevant for applications requiring strong flux pinning, and hence enhanced critical current density and resilient levitation forces, such as maglev systems, magnetic resonance imaging and nuclear magnetic resonance magnets. Improving the performance of YBCO for such applications is commonly achieved by enhancing the flux pinning properties through various mechanisms. In addition, either related to the sample fabrication process or demanded by the final operation conditions, machining these highly brittle samples would be desirable for a number of applications and is a challenging demand. This work reports on the use of ultrashort-pulsed laser irradiation to machine holes into top-seeded melt-growth YBCO samples and how this processing affects their microstructure and superconducting behavior. The x-ray diffraction (XRD) and scanning electron microscopy results demonstrate that ultrashort-pulsed laser machining can create well-defined holes with diminishing microstructural damage. The superconducting properties of the laser-machined samples are essentially preserved, even compatible with the enhancement in the critical current density and levitation force properties. These findings demonstrate the potential of ultrashort-pulsed lasers as a viable tool for machining textured YBCO products and enhancing their performance without degrading their functional properties. This method paves the way towards the generation of artificial defects, machining and shaping of high
superconductor ceramics into precisely well-defined complex geometries relevant for power applications.
The following article is
Open access
SCSC-IFB cable: a novel low-AC-loss cable composed of multifilament coated conductors with superconducting inter-filament bridges
Naoyuki Amemiya
et al
2026
Supercond. Sci. Technol.
39
045010
View article
, SCSC-IFB cable: a novel low-AC-loss cable composed of multifilament coated conductors with superconducting inter-filament bridges
PDF
, SCSC-IFB cable: a novel low-AC-loss cable composed of multifilament coated conductors with superconducting inter-filament bridges
Current sharing between filaments is necessary in multifilament coated conductors to bypass local defects arising from the fabrication process and to impede current transport in each filament. We propose a novel cable concept, termed the spiral copper-plated striated coated conductor with inter-filament bridges cable (SCSC-IFB cable). In this design, copper-plated multifilament (striated) coated conductors incorporating IFBs—non-striated sections between filaments—are helically wound around a central core. In contrast to current sharing through copper plating,
i.e.
, the current meandering through it to avoid local defects on filaments, which generates a small but finite voltage, current sharing through IFBs produces no voltage and thereby does not affect the electric field–current characteristics of multifilament coated conductors. Similar to twisting in conventional low
superconductors, helical cabling decouples filaments electromagnetically against a transverse alternating current (AC) magnetic field. We experimentally confirmed that IFBs improve the electric field–current characteristics,
i.e.
, the
-values, and that the helical cabling does not affect them, by using 2 mm-wide copper-plated 10-filament coated conductors with IFBs. Using the same coated conductors, we wound short pieces of the monolayer SCSC-IFB cables and examined their AC loss characteristics under a transverse AC magnetic field at 77 K. Importantly, the bridge intervals were designed to exceed half the cabling pitch, preventing superconducting loop currents through two IFBs that could otherwise couple the filaments. The measured coupling time constant was 19
s, which is sufficiently small for a wide range of applications. Furthermore, the magnitudes of the measured magnetisation losses above the penetration field of each filament are nearly identical to the theoretical values predicted for cables composed of multifilament coated conductors with electromagnetically decoupled filaments.
The following article is
Open access
Superconducting low-beta Nb
Sn cavity for ATLAS and future ion accelerators
T Petersen
et al
2026
Supercond. Sci. Technol.
39
045006
View article
, Superconducting low-beta Nb3Sn cavity for ATLAS and future ion accelerators
PDF
, Superconducting low-beta Nb3Sn cavity for ATLAS and future ion accelerators
We report on a Nb
Sn-coated low-beta superconducting radio frequency (RF) cavity intended for accelerating ions. We aim to apply the cavity in ATLAS, our Argonne National Laboratory user facility for nuclear physics studies with ion beams in the energy range of 5–20 MeV u
−1
. The Nb
Sn-coated cavity, a 145 MHz quarter-wave optimized for ions moving with velocity
exhibits an order-of-magnitude reduction in RF losses into helium at
compared to a superconducting niobium (Nb) cavity at the same frequency and temperature. Experimentally measured fields are among the highest to date for any Nb
Sn-coated cavity, reaching a peak surface magnetic field of 105 mT. We also present a practical solution to the problem of cavity frequency tuning. Tuning by mechanical deformation has been a challenge with Nb
Sn due to its brittle nature, however, using a set of techniques tailored to the properties of thin-film Nb
Sn on Nb, we can repeatably tune the cavity to the ATLAS master clock frequency after it is cooled, while maintaining the excellent performance characteristics. The same Nb
Sn cavity technology offers broad benefits for future ion accelerators.
More Open Access articles
An efficient 3D finite element method model based on the
T–A
formulation for superconducting coated conductors
Huiming Zhang
et al
2017
Supercond. Sci. Technol.
30
024005
View article
, An efficient 3D finite element method model based on the T–A formulation for superconducting coated conductors
PDF
, An efficient 3D finite element method model based on the T–A formulation for superconducting coated conductors
An efficient three dimensional (3D) finite element method numerical model is proposed for superconducting coated conductors. The model is based on the
T–A
formulation and can be used to tackle 3D computational challenges for superconductors with high aspect ratios. By assuming a sheet approximation for the conductors, the model can speed up the computational process. The model has been validated by established analytical solutions. Two examples with complex geometries, which can hardly be simulated by the 2D model, are given. The model could be used to characterise and design large-scale applications using superconducting coated conductors, such as high field magnets and other electrical devices.
VIPER: an industrially scalable high-current high-temperature superconductor cable
Zachary S Hartwig
et al
2020
Supercond. Sci. Technol.
33
11LT01
View article
, VIPER: an industrially scalable high-current high-temperature superconductor cable
PDF
, VIPER: an industrially scalable high-current high-temperature superconductor cable
High-temperature superconductors (HTS) promise to revolutionize high-power applications like wind generators, DC power cables, particle accelerators, and fusion energy devices. A practical HTS cable must not degrade under severe mechanical, electrical, and thermal conditions; have simple, low-resistance, and manufacturable electrical joints; high thermal stability; and rapid detection of thermal runaway quench events. We have designed and experimentally qualified a vacuum pressure impregnated, insulated, partially transposed, extruded, and roll-formed (VIPER) cable that simultaneously satisfies all of these requirements for the first time. VIPER cable critical currents are stable over thousands of mechanical cycles at extreme electromechanical force levels, multiple cryogenic thermal cycles, and dozens of quench-like transient events. Electrical joints between VIPER cables are simple, robust, and demountable. Two independent, integrated fiber-optic quench detectors outperform standard quench detection approaches. VIPER cable represents a key milestone in next-step energy generation and transmission technologies and in the maturity of HTS as a technology.
The following article is
Open access
Superconducting nanowire single-photon detectors: physics and applications
Chandra M Natarajan
et al
2012
Supercond. Sci. Technol.
25
063001
View article
, Superconducting nanowire single-photon detectors: physics and applications
PDF
, Superconducting nanowire single-photon detectors: physics and applications
Single-photon detectors based on superconducting nanowires (SSPDs or SNSPDs) have rapidly emerged as a highly promising photon-counting technology for infrared wavelengths. These devices offer high efficiency, low dark counts and excellent timing resolution. In this review, we consider the basic SNSPD operating principle and models of device behaviour. We give an overview of the evolution of SNSPD device design and the improvements in performance which have been achieved. We also evaluate device limitations and noise mechanisms. We survey practical refrigeration technologies and optical coupling schemes for SNSPDs. Finally we summarize promising application areas, ranging from quantum cryptography to remote sensing. Our goal is to capture a detailed snapshot of an emerging superconducting detector technology on the threshold of maturity.
World record 32.35 tesla direct-current magnetic field generated with an all-superconducting magnet
Jianhua Liu
et al
2020
Supercond. Sci. Technol.
33
03LT01
View article
, World record 32.35 tesla direct-current magnetic field generated with an all-superconducting magnet
PDF
, World record 32.35 tesla direct-current magnetic field generated with an all-superconducting magnet
We have successfully reached the world record 32.35 T direct-current magnetic field by using a homemade all-superconducting magnet. The magnet has consisted of a 15 T low temperature superconductor outsert coil and two high temperature superconductor no-insulation (NI) insert coils using a conductor tape coated of REBCO (REBa
Cu
, where RE = Y, Gd). This result proves the feasibility of reaching a strong magnetic field up to 32 T by using the NI process as well as the superconductor magnet with insulation. This magnet is one of the essential parts of the ‘Synergetic Extreme Condition User Facility’ project, which provides expertize, instrumentation, and infrastructure for investigating matter science under extreme physical conditions. We thought that such a strong superconductor magnet would bring the possibility to explore more mystery in physics, medicine, pharmacy, etc.
A review of commercial high temperature superconducting materials for large magnets: from wires and tapes to cables and conductors
D Uglietti 2019
Supercond. Sci. Technol.
32
053001
View article
, A review of commercial high temperature superconducting materials for large magnets: from wires and tapes to cables and conductors
PDF
, A review of commercial high temperature superconducting materials for large magnets: from wires and tapes to cables and conductors
High temperature superconducting (HTS) materials have the potential to generate a magnetic field beyond the level obtainable with low temperature superconducting (LTS) materials. This review reports on past and present R&D on HTS cables and conductors for high field tokamaks, accelerator dipoles, and large solenoids. Among the HTS wires and tapes available commercially, coated conductor tapes are the most appealing because of their outstanding critical strength and future improvement margin. Limitations are the weakness against peeling and delamination and the short piece length. The prices of technical superconductors are reviewed because they play an important role in large projects; moreover HTS wires and tapes are discussed from the perspective of industrial production considering the historical development of the LTS wire market. Various designs have been proposed for HTS cables and conductors: some are better suited for soft materials, while others can exploit the anisotropy of coated conductors (by aligning the tape with the field), thus providing the highest current density. Recently, there has been an increase in the size and complexity of the prototypes; however some peculiar features of HTS, such as high stability margins and high mechanical limits, have not yet been fully incorporated into the designs: for example the transposition requirements for HTS have not yet been studied in detail. There are elements indicating that rectangular wires and tapes (even if anisotropic) can be used for manufacturing cables and magnets of any size and have advantages with respect to round wires.
Superconductors for fusion: a roadmap
Neil Mitchell
et al
2021
Supercond. Sci. Technol.
34
103001
View article
, Superconductors for fusion: a roadmap
PDF
, Superconductors for fusion: a roadmap
With the first tokamak designed for full nuclear operation now well into final assembly (ITER), and a major new research tokamak starting commissioning (JT60SA), nuclear fusion is becoming a mainstream potential energy source for the future. A critical part of the viability of magnetic confinement for fusion is superconductor technology. The experience gained and lessons learned in the application of this technology to ITER and JT60SA, together with new and improved superconducting materials, is opening multiple routes to commercial fusion reactors. The objective of this roadmap is, through a series of short articles, to outline some of these routes and the materials/technologies that go with them.
Effect of graphene oxide doping on superconducting properties of bulk MgB
Sudesh
et al
2013
Supercond. Sci. Technol.
26
095008
View article
, Effect of graphene oxide doping on superconducting properties of bulk MgB2
PDF
, Effect of graphene oxide doping on superconducting properties of bulk MgB2
In the present paper we report the effect of graphene oxide (GO) doping on the structural and superconducting properties of MgB
. Bulk polycrystalline samples have been synthesized via a solid state reaction route with compositions MgB
wt% of GO (
= 0, 1, 2, 3, 5, 7 and 10) by sintering at ∼850 ° C in a reducing atmosphere of Ar/H
(9:1). The x-ray diffraction results confirm the formation of the MgB
phase in all samples, together with traces of a MgO impurity phase. The XRD data results also show substitution of carbon for boron, but in the present case the actual amount of carbon substituting for boron is very small as compared to other carbon sources. A substantial improvement in the critical current density,
), has been observed in the entire magnetic field range (0–8 T) for samples
= 1, 2 and 3 as compared to the undoped sample. In addition to
), marginal improvements in the upper critical field (
c2
) and the irreversibility field (
irr
) have been observed for the doped samples
= 1, 2 and 3 with respect to pristine MgB
. Furthermore, a curious result of the present investigation is that there is no change in the superconducting transition temperature (
) up to a doping level of 10 wt%. The possible mechanisms of flux pinning and correlations between the observed superconducting properties and structural characteristics of the samples have been described and discussed in this paper.
The following article is
Open access
High power density superconducting rotating machines—development status and technology roadmap
Kiruba S Haran
et al
2017
Supercond. Sci. Technol.
30
123002
View article
, High power density superconducting rotating machines—development status and technology roadmap
PDF
, High power density superconducting rotating machines—development status and technology roadmap
Superconducting technology applications in electric machines have long been pursued due to their significant advantages of higher efficiency and power density over conventional technology. However, in spite of many successful technology demonstrations, commercial adoption has been slow, presumably because the threshold for value versus cost and technology risk has not yet been crossed. One likely path for disruptive superconducting technology in commercial products could be in applications where its advantages become key enablers for systems which are not practical with conventional technology. To help systems engineers assess the viability of such future solutions, we present a technology roadmap for superconducting machines. The timeline considered was ten years to attain a Technology Readiness Level of 6+, with systems demonstrated in a relevant environment. Future projections, by definition, are based on the judgment of specialists, and can be subjective. Attempts have been made to obtain input from a broad set of organizations for an inclusive opinion. This document was generated through a series of teleconferences and in-person meetings, including meetings at the 2015 IEEE PES General meeting in Denver, CO, the 2015 ECCE in Montreal, Canada, and a final workshop in April 2016 at the University of Illinois, Urbana-Champaign that brought together a broad group of technical experts spanning the industry, government and academia.
The following article is
Open access
The T-A formulation: an efficient approach to model the macroscopic electromagnetic behaviour of HTS coated conductor applications
Felix Huber
et al
2022
Supercond. Sci. Technol.
35
043003
View article
, The T-A formulation: an efficient approach to model the macroscopic electromagnetic behaviour of HTS coated conductor applications
PDF
, The T-A formulation: an efficient approach to model the macroscopic electromagnetic behaviour of HTS coated conductor applications
In recent years, the
T-A
formulation has emerged as an efficient approach for modelling the electromagnetic behaviour of high-temperature superconductor (HTS) tapes in the form of coated conductors (CCs). HTS CCs are characterized by an extremely large width-to-thickness ratio of the superconducting layer, normally up to 1000 ∼ 6000, which in general leads to a very large number of degrees of freedom. The
T-A
formulation considers the superconducting layer to be infinitely thin. The magnetic vector potential
is used to calculate the magnetic field distribution in all simulated domains. The current vector potential
is used to calculate the current density in the superconducting layer, which is a material simulated with a highly nonlinear power-law resistivity. This article presents a review of the
T-A
formulation. First, the governing equations are described in detail for different cases (2D and 3D, cartesian and cylindrical coordinates). Then, the literature on the implementation of
T-A
formulation for simulating applications ranging from simple tape assemblies to high field magnets is reviewed. Advantages and disadvantages of this approach are also discussed.
Status of CORC
cables and wires for use in high-field magnets and power systems a decade after their introduction
D C van der Laan
et al
2019
Supercond. Sci. Technol.
32
033001
View article
, Status of CORC® cables and wires for use in high-field magnets and power systems a decade after their introduction
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, Status of CORC® cables and wires for use in high-field magnets and power systems a decade after their introduction
High-field, low-inductance superconducting magnets in particle accelerators and fusion machines require high operating currents, often in combination with high current densities and for some applications conductor bending radii of less than 50 mm. These requirements form a major challenge for magnet conductors consisting of high-temperature superconductors, which are required for reaching magnetic fields exceeding 20 T, or allowing for operating temperatures above 20 K. The high tolerance of RE-Ba
Cu
7−
coated conductors to axial tensile and compressive strain has led to the concept of CORC
cables in an attempt to develop a round and mechanically as well as electrically isotropic, high-performance conductor that would meet these challenging requirements. This review article will outline how CORC
cables evolved from a concept into a practical and robust conductor for high-field magnets and compact superconducting power cables. This review article provides an extensive overview of how CORC
cable technology has overcome most of the challenges associated with its use in large magnets for fusion, particle accelerators and in helium gas cooled power and fault current limiting cables, while further development is ongoing that will push the CORC
cable technology to even higher performance levels.
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1988-present
Superconductor Science and Technology
doi: 10.1088/issn.0953-2048
Online ISSN: 1361-6668
Print ISSN: 0953-2048